Diet and IBD: What the research says

BBC-crohn's Logo

Every time misinformation about IBD hits the media, you can be sure that the entire IBD community is up in arms – and rightly so! This happened today after BBC reported that junk food may be the cause of Crohn’s.  What?? Junk food is the cause of Crohn’s disease??

Now, before I say my piece on this, let it be clear that these are my own opinions, and I’m not an expert. I’m just a guy with Crohn’s who’s looking for answers.  I think that finding the cause of IBD is the first step in developing a real cure.  I hope that this post will spark discussion, not finger-pointing, not shaming, not a loss of friends or a break in the community.  We all want the same thing, let’s just use our heads to get there. 

I’d like to start by asking everyone who was offended by the BBC piece to just take a collective, deep-breath 

I understand your anger and frustration at the media, but I don’t believe the uproar was justified, and let me explain why: To begin with, neither the BBC article or the TV broadcast suggested that IBD is caused by junk food.  The article quoted Dr. Sally Mitton as saying, “… we also know that lifestyle factors like eating a lot of junk food or taking many courses of antibiotics may make it more likely to happen.”  

And she’s right!  There are many studies which link what we eat (and our antibiotic use) to the RISKS of getting IBD.  

None of them say there is an absolute causal link, but there is a link nonetheless.  

If you’re new to reading statistics, here’s a quick explanation on how the odds ratio works:  Epidemiology – Odds Ratio (OR)

Let’s look at the research done in the past several decades about IBD risk factors in relation to diet.  

I will list the links to the sources at the end of this post. In this meta-analysis, which looked at 19 studies on IBD and diet, the paper “Dietary intake and risk of developing inflammatory bowel disease: a systematic review of the literature.” [1] concluded that:

“High dietary intakes of total fats, PUFAs, omega-6 fatty acids, and meat were associated with an increased risk of CD and UC. High fiber and fruit intakes were associated with decreased CD risk, and high vegetable intake was associated with decreased UC risk.”

You know which foods tend to be high in PUFA’a (polyunsaturated fatty acids) and omega-6 fatty acids? Junk food.  Fried food, chips, pastries, crackers, foods with added vegetable oil.  

What about omega-6 fatty acids? Fried food, chips, pastries, crackers, foods with added vegetable oil.

Total fats? You guessed it, fried food, chips, most meats, candies, JUNK FOOD.

What about negative associations? Which foods are high in fiber? Fruits, vegetables, legumes, whole grains – not junk food (unless fiber is added, but that doesn’t cancel out the risk).

The next study, published in 1998 and titled “‘Modern life’ in the epidemiology of inflammatory bowel disease: a case-control study with special emphasis on nutritional factors.” [2] found that:

“A positive association with cola drinks [OR: 2.2 (95% Cl 1.5-3.1)], chewing gum [OR: 1.5 (95% Cl: 1.1-2.1)] and chocolate consumption [OR: 2.5 (95% Cl: 1.8-3.5)] and a negative association with citrus fruit consumption [OR: 0.5 (95% Cl 0.3-0.7)] and the development of Crohn’s disease were found. Consumption of cola drinks [OR: 1.6 (95% Cl 1.1-2.3)] and chocolate consumption [OR: 2.5 (95% Cl 1.8-3.5)] were positively associated with developing ulcerative colitis.”

Again, junk food seems to increase the risks of both Crohn’s and Ulcerative Colitis, while fruit (in this case, citrus) reduces the risks.

In children, we also have data which supports the suggestion that bad foods can increase the risk of IBD, like in this 2007 study titled “Dietary patterns and risk for Crohn’s disease in children” [3].  

The author’s found that:

“Pattern 1 in girls, characterized by meats, fatty foods, and desserts, was positively associated with CD (OR 4.7, 95% CI 1.6–14.2). Pattern 2, common to both boys and girls, was characterized by vegetables, fruits, olive oil, fish, grains, and nuts and was inversely associated with CD in both genders (girls: OR 0.3, 95% CI 0.1–0.9; boys: OR 0.2, 95% CI 0.1–0.5).”

Fatty foods? Desserts? Sounds like junk food to me.  

Meats are also linked in this large prospective study, “Animal protein intake and risk of inflammatory bowel disease: The E3N prospective study.” [4] and they also discovered that:

“High total protein intake, specifically animal protein, was associated with a significantly increased risk of IBD, (hazards ratio for the third vs. first tertile and 95% confidence interval being 3.31 and 1.41-7.77 (P trend=0.007), and 3.03 and 1.45-6.34 (P trend=0.005) for total and animal protein, respectively). Among sources of animal protein, high consumption of meat or fish but not of eggs or dairy products was associated with IBD risk.”

And let’s not forget this case-controlled Japanese study [5], which also discovered that:

“In the food groups, a higher consumption of sweets was positively associated with UC risk [OR for the highest versus lowest quartile, 2.86; 95% confidence interval (CI), 1.24 to 6.57], whereas the consumption of sugars and sweeteners (OR, 2.12; 95% CI, 1.08 to 4.17), sweets (OR, 2.83; 95% CI, 1.38 to 5.83), fats and oils (OR, 2.64; 95% CI, 1.29 to 5.39), and fish and shellfish (OR, 2.41; 95% CI, 1.18-4.89) were positively associated with CD risk.”

Sweets, oils, sweeteners? Don’t find much of that in whole foods, do we? And finally, this study, titled “Diet and inflammatory bowel disease: a case-control study.” [6]  found that:

“The most striking finding was an increased relative risk of both Crohn’s disease and ulcerative colitis associated with consumption of fast foods: the relative risk associated with consumption of fast foods at least two times a week was estimated at 3.4 (95% confidence interval = 1.3-9.3) for Crohn’s disease and 3.9 (95% confidence interval = 1.4-10.6) for ulcerative colitis.”


Who’s more likely to eat fast food? Teens and young adults. [7] Who’s most affected with IBD? Teens and young adults [8].    

What about infants who are born with IBD?

We may find a link between maternal diets and the risks of developing IBD at some point.  

We know that what a mother eats CAN affect the health of their child long into adulthood [9], so there is a potential risk that needs to be further investigated when it comes to IBD.

While we can’t say that junk food CAUSES Crohn’s or Ulcerative colitis, we can say that there seems to be a link in the risk factors associated with IBD and the consumption of processed foods.

Could diet be one piece to the large and complex puzzle of IBD? Of course!  It’s already been suggested that the foods we eat can have a positive or negative impact on our intestinal microflora, lending to the risks associated to IBD and other illnesses.  

One study that explored this relationship stated that:

“While it is conceivable that excessive omega-6 PUFA consumption is linked to increased IBD risk, the assumption made is that dietary fatty acids directly alter the host’s intestinal immune responses. While this is likely, it is also plausible that such an effect, at least in part, is due to shifts in the ecology of the gut microbiota. Both the microbiota and the intestinal mucosa are exposed to dietary antigens, suggesting the possibility that IBD susceptibility could be influenced by diet through the type of microbes that are influenced by nutritional factors.”  [10]

So was the BBC wrong about what they wrote? I don’t think so.  

Could it have been stressed that they were talking about risks, not absolute cause? Sure, but they already said that on video.  We need to think before we jump on the (often uneducated) media about issues revolving around IBD; especially when it comes to the causes and treatments.  

We need to discuss these things constructively, not light fires under the beds of reporters.

As I write this, I want to make it clear that I don’t blame ANYONE for their IBD.  

How we got it remains a mystery that I hope we can solve through research.

The more we learn, the more we can prevent and treat this terrible illness.  

And as we reveal more about how food affects our gut flora, the implications of diet vs. disease and how other environmental factors may contribute to the risks associated with IBD, we must continue to openly share new information without being defensive or offended about it.

UPDATE (Dec 18, 2015): Meta-analysis on meat: 2015 study.

This very recent meta-analysis, which compiled nine high-quality studies, reaffirmed that “high
intake of meat is associated with an increased IBD risk.” [12].  One thing to note is that because many of the studies in this meta-analysis were from Asian countries, “high” meat consumption would be much lower than the way Westerners tend to eat, which could explain the much higher rates of IBD in Western countries.

UPDATE (Sept 30, 2014):  What about carbs?

An interesting new study which looked at over 400,000 people to see if carbohydrate intake increased the risk of IBD [11] found that carbs, including starch, didn’t have any role in the development of IBD. I’m not too surprised, given that plant-foods are generally protective, as we’ve seen from the other studies, but it does raise a question for those who are using low-carb diets to treat their illness.


1. Hou JK, Abraham B, El-Serag H. Dietary intake and risk of developing inflammatory bowel disease: a systematic review of the literature. Am J Gastroenterol. 2011 Apr;106(4):563-73. doi: 10.1038/ajg.2011.44. Review. PubMed PMID: 21468064.

2. Russel MG, Engels LG, Muris JW, Limonard CB, Volovics A, Brummer RJ, Stockbrügger RW. Modern life’ in the epidemiology of inflammatory bowel disease: a case-control study with special emphasis on nutritional factors. Eur J Gastroenterol Hepatol. 1998 Mar;10(3):243-9. PubMed PMID: 9585029.

3. D’Souza S, Levy E, Mack D, Israel D, Lambrette P, Ghadirian P, Deslandres C, Morgan K, Seidman EG, Amre DK. Dietary patterns and risk for Crohn’s disease in children. Inflamm Bowel Dis. 2008 Mar;14(3):367-73. PubMed PMID: 18092347.

4. Jantchou P, Morois S, Clavel-Chapelon F, Boutron-Ruault MC, Carbonnel F. Animal protein intake and risk of inflammatory bowel disease: The E3N prospective study. Am J Gastroenterol. 2010 Oct;105(10):2195-201. doi: 10.1038/ajg.2010.192. Epub 2010 May 11. PubMed PMID: 20461067.

5. Sakamoto N, Kono S, Wakai K, Fukuda Y, Satomi M, Shimoyama T, Inaba Y, Miyake Y, Sasaki S, Okamoto K, Kobashi G, Washio M, Yokoyama T, Date C, Tanaka H; Epidemiology Group of the Research Committee on Inflammatory Bowel Disease in Japan. Dietary risk factors for inflammatory bowel disease: a multicenter case-control study in Japan. Inflamm Bowel Dis. 2005 Feb;11(2):154-63. PubMed PMID: 15677909.

6. Persson PG, Ahlbom A, Hellers G. Diet and inflammatory bowel disease: a case-control study. Epidemiology. 1992 Jan;3(1):47-52. PubMed PMID: 1313310.

7.  Fast-food consumption among US adults and children: Dietary and nutrient intake profile

8. The FACTS ABOUT Inflammatory Bowel Diseases 8. Nutrition and the Epigenome

9. Nutrition and the Epigenome

10.  Diet-Induced Dysbiosis of the Intestinal Microbiota and the Effects on Immunity and Disease Kirsty Brown, Daniella DeCoffe, Erin Molcan, Deanna L. Gibson Nutrients. 2012 August; 4(8): 1095–1119. Published online 2012 August 21. doi: 10.3390/nu4081095 Correction in: Nutrients. 2012 November; 4(11): 1552–1553. PMCID: PMC3448089

11. Chan SS, Luben R, van Schaik F, Oldenburg B, Bueno-de-Mesquita HB, Hallmans G, Karling P, Lindgren S, Grip O, Key T, Crowe FL, Bergmann MM, Overvad K, Palli D, Masala G, Khaw KT, Racine A, Carbonnel F, Boutron-Ruault MC, Olsen A, Tjonneland A, Kaaks R, Tumino R, Trichopoulou A, Hart AR.Carbohydrate Intake in the Etiology of Crohn’s Disease and Ulcerative Colitis.Inflamm Bowel Dis. 2014 Sep 26. [Epub ahead of print] PubMed PMID: 25265262.

12. Ge J, Han TJ, Liu J, Li JS, Zhang XH, Wang Y, Li QY, Zhu Q, Yang CM. Meat intake and risk of inflammatory bowel disease: A meta-analysis. Turk J Gastroenterol. 2015 Nov;26(6):492-7. doi: 10.5152/tjg.2015.0106. PubMed PMID: 26575042.

2 thoughts on “Diet and IBD: What the research says”

  1. I don’t think it is one thing. It doesn’t explain why people like Frank’s son at 2 months or myself at 10 months ended up with IBD since we barely had a diet to begin with. There are also a ton of people out there with terrible diets that never end up with IBD. Diet may be a contributing factor in some way but is surely not the cause alone like you said. I agree with you that the article did not say poor diet causes IBD. Which is why when I saw this yesterday I had nothing to say about it because she didn’t say IBD is caused by junk food. She said it may make it happen and who knows if by that she meant it may contribute or it may aggrivate it.

    • And I think that’s why we need to read, investigate then comment (in that order!). We know that things like smoking, for example, can trigger some pretty nasty problems, but you’ll always have the one person who says “yeah, but my 90 year old uncle smoked all the time and he was healthy!”. Does that mean cigarettes are safe? Of course not.

      We have to stop looking at IBD being caused by a single thing; it’s a bunch of risk-factors that may all have equal or completely disproportionate weights to them.

      The Mayo Clinic lists the following as risk factors:
      – age
      – ethnicity
      – family history
      – previous medications (Accutane, antibiotics, etc.).
      – smoking
      – the use of NSAID’s
      – even your geographical location

      You can’t say “well, I smoke and I don’t have IBD”… that misses the point completely in that it’s a risk factor not a absolute cause.


Leave a comment. (Your email will not be published)